You gave a lot of clues. It looks like poo, it smelled like poo, and was the size of a hamburger. I think I could guess it if it tasted like poo. I'm thinking it doesn't because...my dear Watson
without that clue I'm leaning towards one of mine or Pesky's co-horts possibly another wco made it with a foam gun purchased from Phil Nichols. Then threw a little stink on it know knowing you would smell it. They didn't worry about the taste because they were pretty sure you wouldn't taste it. They knew we all loved mystery's and would spend a lot of time on it while they were out making money with their foam guns.
Check and see if it breaks. When you break it you can tell its foam. Maybe see if your dog will roll on it. Finally shoot the stuff that is one sure way to tell if its real. I am pretty sure its not bull stuff because that is more the size of a pizza and I've been around a lot of it. If you can't figure it out wrap it in some charmin send it to me in a plain brown wrapper I think I can figure it out. I have a masters in shtology
Sleep'n with an animal..I can help.
Do not use both feet when testing the depth or temperature of the water